DESCRIPTION (From the Applicant?s Abstract): Pseudomonas produces several virulence factors that are important for the organism to survive in the host and cause keratitis, and the study of these identified factors plus previously unidentified factors is important for understanding the mechanisms of ocular disease caused by Pseudomonas. The aims of this proposal are 1)to determine the functions in protein transport and folding of the propeptide domain of protease IV, an enzyme that has been implicated as a virulence factor in keratitis caused by Pseudomonas aeruginosa, and 2)to isolate and identify an uncharacterized protease from P. aeruginosa that could be important for understanding this form of keratitis. The protease IV propeptide domain will be cloned, expressed, and purified for the purpose of making an antibody to it, and its location in the bacterial cell will be determined. The propeptide?s possible function in mature protease IV secretion will also be analyzed. An unknown protease that has been observed on zymograms of Pseudomonas extracts will be isolated and its N-terminus sequenced for comparison to the published sequence of P. aeruginosa.